Field of the Invention
The present invention relates to an agricultural machine for the harvesting of plants comprising:                a chassis,        at least one harvesting mechanism connected to the chassis and comprising:        a cutting mechanism comprising cutting elements intended for cutting plants, and        a conditioning device comprising first and second contra-rotating conditioning elements liable to move away from one another and between which the plants cut by the cutting elements are intended to pass for their treatment,        a transmission mechanism intended to ensure the driving of the cutting elements and of the first and second conditioning elements, and comprising:        a primary box comprising:        a primary casing delimiting a primary inner volume,        an input shaft provided to be set in motion from a power source,        a first primary output connected to the cutting mechanism,        a second primary output connected to the first conditioning element,        a third primary output,        primary torque transmission means connecting with one another the input shaft, the first primary output, the second primary output and the third primary output, and housed within the primary casing,        a secondary box comprising:        a secondary casing delimiting a secondary inner volume,        a secondary input connected to the third primary output,        a secondary output connected to the second conditioning element,        secondary torque transmission means connecting with one another the secondary input and the secondary output, and housed within the secondary casing,        a lubrication device for the primary box comprising:        a fluid lubricant,        a pump sucking up the lubricant contained in the primary box,        a primary distribution system communicating with the primary inner volume and supplied with lubricant by the pump, by means of which primary distribution system the lubricant is distributed towards at least part of the primary torque transmission means.        
Discussion of the Background
Such a machine is known from the document FR 2 751 166 A1. This machine comprises a harvesting mechanism which is composed of a frame carrying a cutting mechanism at the rear of which two pairs of contra-rotating conditioning elements extend. The conditioning elements of one pair are situated one above the other. One of them, in this case the lower conditioning element, is driven about a rotation axis which is fixed with respect to the cutting mechanism, whereas the upper conditioning element is mounted on a rotation axis which is movable with respect to the cutting mechanism so as to be able to allow a variable volume of cut plants to pass. A primary box extends between these two pairs of conditioning elements in a substantially central manner within the harvesting mechanism. This primary box ensures the driving, on one hand, of the cutting mechanism, by means of a first primary output situated at the front of the primary box, on another hand, of each lower conditioning element, by means of a respective second primary output. Each upper conditioning element is driven from a respective secondary box pivotably mounted on a respective lateral end of the harvesting mechanism. For this purpose, each secondary box comprises on one hand a secondary input connected, by means of a transmission shaft extending over the entire working width of the corresponding upper conditioning element, to a respective third primary output of the primary box, and on another hand a secondary output connected to the upper conditioning element. Furthermore, there is provided a lubrication device for the primary box operating with a fluid lubricant such as oil. This lubricant is in part set in motion by means of a pump housed in the primary box. This pump is connected to a primary distribution system formed by a duct, in particular a pipe, communicating with an upper end of the primary box so as to lubricate, by circulation of the lubricant in a closed circuit within the primary box, the primary torque transmission means contained in the primary box and extending over the height thereof, formed in particular by gears, shafts and bearings. The secondary box is a substantially sealed box which does not communicate with the primary box and which likewise contains a lubricant in order to lubricate the secondary torque transmission means contained in the secondary box.
This lubrication of the secondary box distinct from that of the primary box has a certain number of drawbacks.
The periodic operations of checking the quantity and/or of replacement of the lubricant are doubled, since they are required for each box. This multiplicity of maintenance operations is tedious for the user, increases the time that the machine is out of service, and increases the risk of omitting or neglecting the maintenance of one of the boxes.
Furthermore, the lubricant contained in the secondary box is confined inside of the inner volume of this secondary box, this inner volume is, however, of small size. The overall dimension of the secondary box is indeed greatly dictated by the distance between the rotation axis of the upper conditioning element on one hand, and the transmission shaft connected to the primary box on another hand. So as to limit the overall dimension of the harvesting mechanism, in particular in height, this distance is quite small, with the result of a reduced centre-to-centre distance between the secondary input and the secondary output of the secondary box. The overall dimension of the latter is also limited, in its lower part, by the very close presence of the rotational mounting means of the lower conditioning element on the frame of the harvesting mechanism. These various geometric constraints greatly reduce the size of the secondary box and therefore the heat exchange surface towards the ambient air through its walls. The secondary box in its entirety, and the lubricant which it contains, are therefore liable to be subject to a great heating during the work of the machine. In addition, in the case of a fluid lubricant in which the secondary torque transmission means are in part bathed, these geometric constraints reduce the inner volume of the secondary box, within which this lubricant can be distributed, and in particular the space between the secondary torque transmission means and the walls of the secondary box. There then arises a delicate compromise to be solved between, on one hand, a large quantity of lubricant in order to ensure a sufficient supply with lubricant of the secondary torque transmission means bathing in part in this lubricant, this large volume of lubricant in which the secondary torque transmission means paddle during their movement being able nevertheless to generate an excessive heating and an accelerated degradation of the lubricant by shearing and friction, and on another hand a reduced quantity of lubricant, which can nevertheless result in an insufficient lubrication under certain conditions. Furthermore, a fluid lubricant confined inside of the secondary box is projected on the internal walls of the box by the secondary torque transmission means in rotation. This phenomenon is liable to produce a lack of lubrication of these transmission means, because the lubricant can distribute itself, essentially, on the internal walls and not on the secondary torque transmission means. The problem of the supply with lubricant to the secondary torque transmission means, and also the heating of the lubricant and of the secondary box, arises acutely on a harvesting machine having a large working width and subjected to strict regulations dictating a reduced overall dimension during transport. The large working width requires bulky and heavy conditioning elements, between which a large flow of cut plants passes. This results in an increased mechanical power which the secondary box must transmit towards the corresponding conditioning element. Between the volume occupied by these conditioning elements and the total overall dimension of the machine, fixed in part by the legislator, in particular widthwise, the space remaining available for the secondary casing is reduced. In addition, inside of the latter, secondary torque transmission means dimensioned in an increased manner so as to resist the increased mechanical forces, tend to reduce the available volume for the lubricant. It then becomes difficult to ensure a suitable lubrication and cooling of the secondary box as a whole.